For many years now it has been known in the art to pro vide an engine driven machine serving to extrude properly configured curbing onto the ground, typically onto a previously prepared sur face of a parking lot or the like. Such a machine is provided with steerable front wheels and heightwise adjustable rear wheels, and is further equipped with a hopper into which molten asphalt or already mixed concrete can be poured as the machine is caused to roll slowly along a given line established as the desired location for the curb.
A curb mold is removably attached in a lower rear portion of a machine of this type, and supported in an operational manner in relation thereto is an engine driven, shaft mounted auger. The molten asphalt or concrete poured into the hopper flows through an opening in the bottom of the hopper into the curb mold, with the rotation of the auger under the powerful influence of the engine causing the molten asphalt or concrete to be compacted into the curb mold. As the molten asphalt or concrete is extruded through the rear opening of the curb mold, the wheeled machine is caused in reaction thereto, to move forwardly under the guidance of an operator. The operator typically walks backwardly, while holding a T-handle or equivalent, so that he can readily control the directional attitude of the front wheels of the machine. In this way the operator can either lay a straight curbing, or he can lay the curbing in a curved configuration, as may be required in a particular instance.
The rear wheels of a machine of this type do not support the entire weight of the rear portion of the machine, for the curb mold is equipped with lower edges that slide along in firm contact with the surface of the parking lot or other such location, and the curb mold thus supports a distinct portion of the weight of the machine.
In view of the fact that the lower edges of the curb mold thus carry a substantial portion of the weight of the machine, and the machine may weigh more than 1000 pounds, it would be very difficult for the operator to change direction of movement of the machine without taking some or all of the weight of the rear portion of the machine off of the curb mold. Such a change of direction is obviously necessary from time to time, for although some runs of curbing are straight, it is inevitable that it will be necessary to lay curbing at a different angle to, or in a different relationship with, the prior runs of curbing.
The machine illustrated herein is generally along the lines of a machine manufactured by Power Curbers, Inc. of Salisbury, North Carolina 28144. In a typical Power Curbers machine, the rear wheels are to some degree extensible at the behest of the operator, with the rear wheels in the normal or operative position permitting the lower edges of the curb mold to slide along the ground surface. The rear wheels, however, when extended, cause the rear portion of the machine to move away from the ground surface to a sufficient extent that the lower edges of the curb mold will be free of ground contact. At that point the machine can be turned, or even loaded onto a truck or trailer, for transport to another location.
The height change mechanism utilized in the Power Curbers machine is mechanical, with the operator being provided with a type of crank that is turned manually. When the operator wishes to change the direction in which the machine moves, he or his assistant declutches the auger from the rotative influence of the engine, so that forward motion ceases. The operator then turns the crank in order to effect the extension of the rear wheels with respect to the chassis. This causes the lower edges of the curb mold to move away from ground contact, thus greatly simplifying the task of the operator moving the machine into a new alignment with respect to the parking lot, even to an entirely different location.
Unfortunately, the turning of the crank is a tiring operation, for during the course of laying many dozens if not hundreds of feet of curb in the course of a day, it will be necessary for the operator to crank the machine up and down many times in order that the curbing can be laid in a desired configuration.
It is in an effort to lighten the burden of moving the curb mold away from ground contact at direction changing times that the present invention was evolved.
Of some pertinence is the teaching represented by the Rochfort Pat. No. 3,890,055, entitled "Concrete Laying Machine," which issued as a U.S. Pat. on June 17, 1975.
It is most important to note that Rochfort describes in his Column 2, approximately at line 42, that he utilizes a "pair of height adjusting devices comprising, in this instance a threaded member 42 on the chamber operatively engaged in a correspondingly threaded tubular member or housing 43, each support a side of the body above one of the supporting wheel assemblies 13."
Column 2 of the Rochfort patent continues by stating "The member 43 is pivotally mounted at 44 to bracket 45 on the assembly 13. Actuating means, in this instance, a hydraulic motor 41 is adapted to drive the threaded member 42 whereby the or each side of the body may be raised or lowered."
It is obvious that a great deal of time will necessarily be consumed by Rochfort's elongate threaded members 42 going about raising the Rochfort frame, with a similar amount of time necessarily being consumed at such time as his frame is to be lowered so that the concrete curb laying operation may resume. In addition, exposed threads readily become fouled by dust as well as spilled concrete, necessitating a frequent cleaning of the threads if they are to be kept in operational condition.
In contrast, the present invention utilizes an extensible fluidic actuator, which can be manipulated in a matter of a few seconds, to cause the chassis of his machine to dependably raise and thus remove the lower edges of his curb mold from ground contact. No elongate threaded members, with attendant expense and slow response, are utilized or needed. As soon as the chassis has been raised, the operator can swing the instant curb laying machine to the desired new orientation, and that being accomplished, he can promptly bleed the fluid from the extensible fluidic actuator, so that the lower edges of the curb mold can quickly resume contact with the ground. Immediately after this, the laying of curbing in the new direction can be commenced without further delay.